The present invention relates to solid state imaging systems and, more particularly, to a method for rapidly identifying and measuring objects whose image is sensed by the imaging system.
This application relates to improvements in the method of operation of imaging systems of the type disclosed in U.S. Pat. Nos. 4,240,116 and 4,241,421 both of which are signed as to the assignee of the present invention. Those patents disclose a solid state imaging apparatus of the type commonly referred as a charge injection device (CID) and describe certain electronic processing apparatus for obtaining from the CID imager digital information of the type which can be processed to identify, measure and recognize objects and alpha-numeric characters. The method of operation of this apparatus disclosed in these prior art patents is to individually interrogate each of a plurality of picture elements (pixels) which are formed on a solid state substrate in order to build a picture of an object which has been imaged on the solid state imager. In order to provide an adequate picture of an object using this type of imager, the imager is normally formed of a matrix of solid state pixels which may have as many as 512 rows and 512 columns of pixels. Such a matrix results in excess of 250,000 individual pixels which must be individually interrogated in order to develop an image of an object which has been placed within a field of view of the imager.
Various methods of data processing have been utilized in order to reduce the time required to process data obtained from solid state imagers. One such method has been to use a technique commonly referred to as profile analysis. In profile analysis, the values associated with each pixel of a row are summed together to form a single value for each row of the matrix. Subsequently, the values associated with each pixel in each column are summed together to obtain a profile along the column axis. This type of profile analysis is useful in identifying objects and in providing measurements of the boundaries and/or centroids of objects imaged on the imager. However, in the prior art systems it has been necessary to read each individual pixel into a memory which is part of a data processing system and to subsequently operate on the data stored in the memory to generate the profiles of the objects along the X and Y axis of the imager. Accordingly, it will be appreciated that it is still necessary to read out each individual pixel from the matrix before the profile data can be generated although this technique will reduce the comparison time which is required if the status of each individual pixel is separtely evaluated against stored memory characteristics of an object to be identified.
It is an object of the present invention to provide an improved method of operating a solid state imager which will permit high speed object recognition and identification.
In carrying out the invention in the context of the apparatus disclosed in the aforementioned patents, there is provided a method for reading directly from the solid state imager the values associated with the pixels in each row and in each column of the matrix of pixels without the necessity of having to store the individual pixel values in memory prior to generating the profile data. In particular, a method is provided for non-destructive reading of the pixel values such that each pixel can be summed once during the generation of the profile along the row axes and summed a second time during the generation of the profile along the column axes. The invention is preferably implemented in a CID type of imager which permits a charge transfer within each pixel element without destruction of the charge.